This invention relates to a portable rubbing machine of the type used for sanding or polishing and, more particularly, to a machine in which a support is spaced from and overlies a rectangular rubbing shoe. A drive mechanism is connected between the support and the shoe to drive the latter with a back and forth motion, and a number of flexible boots are connected between the support and the shoe to cause the shoe to move back and forth rather than rotating about the drive mechanism.
A rubbing machine of this general type is disclosed in Champayne U.S. Pat. No. 3,577,687. In the rubbing machine of that patent, the boots are extremely flexible and each houses a pair of relatively movable thrust transmitting members formed by opposing studs. The studs transmit thrust between the shoe and the overlying support so as to relieve the boots of the burden of transmitting the thrust and thereby enable the use of boots which are extremely flexible. The use of very flexible boots significantly reduces the power required to move the rubbing shoe.
The shoe of the rubbing machine of the Champayne patent moves with a gyratory motion. That is, the elongated shoe is moved back and forth in a lengthwise direction and, at the same time, is moved side-to-side. A rubbing machine with a gyratory shoe is preferred for certain operations while, in other applications it is more advantageous to use a rubbing machine having a shoe which reciprocates back and forth along a straight path. A rubbing machine with a reciprocating shoe is disclosed in Champayne U.S. Pat. No. 2,825,188.